/*
 * =============================================================
 *
 *        Project:  apue
 *
 *       Filename:  mask.c
 *
 *         Editor:  vim :set et ts=2 sts=2 sw=2
 *
 *         Author:  Martin Y. Yang , yang@libpix.org
 *
 *    Description:  
 *
 * =============================================================
 */

/**
 * @file
 * @brief Figure 10.20 Example of signal masks, sigsetjmp, and siglongjmp
 */

#include "apue.h"
#include <setjmp.h>
#include <time.h>

static void sig_usr1(int), sig_alrm(int);
static sigjmp_buf jmpbuf;
static volatile sig_atomic_t canjump;

int mask_main(int argc, char *argv[])
{
  if (signal_lib(SIGUSR1, sig_usr1) == SIG_ERR)
    err_sys("signal(SIGUSR1) error");
  if (signal_lib(SIGALRM, sig_alrm) == SIG_ERR)
    err_sys("signal(SIGALRM) error");
  pr_mask("starting main: ");                   /* Figure 10.14 */

  if (sigsetjmp(jmpbuf, 1)) {
    pr_mask("ending main: ");
    exit(0);
  }
  canjump = 1;                                  /* now sigsetjmp() is OK */

  for ( ; ; )
    pause();

}

static void sig_usr1(int signo)
{
  time_t starttime;

  if (canjump == 0)
    return;                                     /* unexpected signal, ignore */

  pr_mask("starting sig_usr1: ");
  alarm(3);                                     /* SIGALRM in 3 seconds */
  starttime = time(NULL);
  for ( ; ; )
    if (time(NULL) > starttime + 5)
      break;
  pr_mask("finishing sig_usr1: ");

  canjump = 0;
  siglongjmp(jmpbuf, 1);                        /* jump back to main, don't return */
}

static void sig_alrm(int signo)
{
  pr_mask("in sig_alrm: ");
}
